The couple, who got engaged in 2011, previously admitted their six children, Maddox, 11, Pax, nine, Zahara, eight, Shiloh, six, and four-year-old twins Knox and Vivienne were putting them under pressure to make their union official.
Brad said: "I am getting more pressure from my kids, and it is something I want to do within their lifetime, but I also feel like the time has come."
The actor praised his fiancee as "heroic" for making the decision to have her breasts removed and reconstructed.
He said: "Having witnessed this decision first hand, I find Angie's choice, as well as so many others like her, absolutely heroic. I thank our medical team for their care and focus.
"All I want for is for her to have a long and healthy life, with myself and our children. This is a happy day for our family."
Angelina decided to be tested for the gene because she lost her 56-year-old mother Marcheline Bertrand to ovarian cancer in 2007.
The Oscar-winning actress now only has a five per cent chance of developing breast cancer and she admitted her children were a big motivation for her to have the surgery because she wants to see them all grow up.
- Bang! Showbiz